Lattice dynamics of tetrahedrally bonded boron nitride probed by inelastic X-ray scattering

We report experimental results on the lattice dynamics of zincblende and wurtzite boron nitride obtained by inelastic X-ray scattering (IXS) on polycrystalline samples. The generalized vibrational density of states and the orientation averaged longitudinal acoustic phonon dispersion are determined, and the longitudinal and shear sound speeds as well as the Debye temperature are derived. Our results are compared to ab initio lattice dynamics calculations and available elastic and thermodynamic data.